In the combustion of a fuel, such as coal, oil, peat, waste, or the like in a combustion plant, such as a power plant or waste-to-energy plant, a hot process gas is generated. Such hot process gas is often referred to as a “flue gas” and contains pollutants, including acid gases, such as sulphur dioxide, SO2. Removal of as much acid gas as possible from the flue gas is necessary before the flue gas may be released to ambient air or the atmosphere. A spray dryer absorber may be utilized for removing acid gases, including sulphur dioxide, from a flue gas.
An example of a spray dryer absorber can be found in U.S. Pat. No. 4,755,366. The spray dryer absorber comprises a chamber equipped with a rotary atomizer having an atomizer wheel. The rotary atomizer is supplied with an aqueous suspension, sometimes referred to as a slurry, which comprises an absorbent, such as limestone. The atomizer wheel spins at a relatively high number of revolutions per minute (rpm) and atomizes the aqueous suspension, such that very small droplets are formed. The formed small droplets absorb acid gas components from the flue gas, and then form a solid residue as a result of the drying effect of the spray dryer absorber.
A problem of the spray dryer absorber of U.S. Pat. No. 4,755,366 is that it is difficult to remove accumulated deposits that form in the spray dryer absorber and its components, such as its dispersers and atomizers, during use. Typically, such cleaning or removal of accumulated deposits requires as many as 4 days to clean six atomizers. Likewise, accumulated deposit removal or cleaning can only be accomplished during a plant outage, such as during a scheduled plant outage or during a forced plant outage. If the accumulated deposits are not removed periodically, the accumulated deposits build and cause interference with the spray dryer absorber's performance. Upon interference with the spray dryer absorber's performance, a forced plant outage is required to clean or remove the accumulated deposits from the spray dryer absorber and its components. Removal of the accumulated deposits is accomplished using mechanical or hydraulic means known to those skilled in the art. As noted above, cleaning or removing accumulated deposits from the SDA and its components using mechanical or hydraulic means requires a significantly great amount of time with significant associated expense.
A device and a method for cleaning accumulated deposits from spray dryer absorbers and spray dryer absorber components, operable without requiring a plant outage, and requiring less time and expense, are needed.